Method of dehydrating emulsions



June 28, 1932. FlSHER 1 1,864,721

METHOD OF DEHYDRATING EMULSIONS Fi'led Aug. 30, 1926 Patented June 28, 1932 v UNITED STATES,

PATENT OFFICE HARMON F. FISHER, LONG BEACH, CALIFORNIA, ASSIGNOR TO PETROLEUM RECTI- FYINGCOMPANY OF CALIFORNIA, OF SAN FRANCISCO, CALIFORNIA, A CORPORA- TION OF CALIFORNIA METHOD OF IDEHYDRA'IING v EMULSIONS Application filed August 30, 1926. Serial No. 132,375.

My invention relates tothe dehydration of petroleum and other oils.

It is well known that petroleum oil as it occurs in nature often carries small particles of water, and it is common practice to remove the particles of water by electrical dehydration. Electrical dehydration processes are used extensively, in which the emulsion of petroleum oil and water is subjected to action in an electric field. This process is commonly carried on in an apparatus having a pair of electrodes immersed in the emulsion and between which electrodes the electric field is established. Masses of water are apparently formed by coalescence between the electrodes, the masses of water precipitating from the oil.

It has been the usual practice to employ in electric dehydrators electric potentials of standard alternating frequencies and wave forms. I have found, while an alternating.

potential of eleven thousand volts having a may be conducted.

frequency of sixty cycles per second and standard sine wave form is quite efficient in treating ordinary oils, that the dehydration can be greatly improved by using in addition a considerably higher potential of short duration, and that this higher potential can be impressed upon the standard form of. treater in addition to the normal potential of standard wave form, potential and frequency, thus giving a combined wave. form having a sharp peak of short duration. This sharp peak or kick may be obtained by several means, some of which are described hereinafter.

Referring to the drawing in which Iillustrate my invention,

Fig. 1 is a very diagrammatic view illustrating an apparatus whereby my process Figs. 2 to 5 inclusive are diagrams showing the characteristics of the different electric fields which maybe produced by the apparatus shown in Fig. 1.

Referring first to Fig. 1 of the drawing, 11 represents a dehydrator which consists of a shell 12 having an emulsion inlet 13, an oil outlet 14 and a water outlet 15.' A primary grounded electrode 16 is electrica 1y connected to the shell 12 and supported by brackets 17 inside the shell 12. Supported within the shell 12 above the primary electrode 16 is a secondary live electrode 19 which is suspended from a wire 20. An insulator 21 is provided in the wire 20 for insulating the secondary electrode 19 from the shell 12. A wire 24 is connected to the wire 20 and passes to the exterior of the shell 12 through an insulator 25. The shell 12 is grounded by means of a wire 28, and therefore the primary elec trode 16 is grounded.

One terminal of the secondary 37, of what I call for convenience a kick transformer, is connected to the wire 24 and hence to the live electrode 19. The other terminal of the secondary 37 is connected to one terminal of a secondary 30 of a main transformer 31. The other terminal of the secondary 30.is grounded as shown at 27 and thus connected through the ground and the wire 28 with the grounded electrode 16. A primary 32 of the main transformer 31 is excited by an alternating current of normal frequency and wave form, so that an alternating potential of, say, 5000 volts is inducedin the secondary 30.

Also included in the primary and secondary electrode circuit is the secondary 37 of the kick transformer 38. A primary 40 of the kick transformer 38 is included in a circuit 41 having a current control means 42. This current control means may be any suitable contact maker and breaker commutating device and current limiting means such as are well known in the art and may be either synchronously operated to effect the wave form shown in Fig. 3, for instance, or may operate promiscuously, in which case no synchronous relation would necessarily exist. The circuit 41 may be excited by eitherdirect current or alternating current, the use of which will be touched on hereinafter. The kick-transformer 38 is designed so that it will create an induced voltage in the secondary 37 thereof, having six to eight times the peak voltage of the main transformer 31.

The main transformer 31 thus supplies a primary potential of substantially sinusoidal wave form to the circuit which includes the electrodes, while the kick transformer 38 supplies a secondary or auxiliary potential of different wave form to this circuit.

The operation of the dehydrator shown in -Fig. 1 is as follows. The emulsion to be dehydrated is introduced into the shell 11 through the pipe 13. The main transformer 31 when energized establishes an alternating current which produces an electric field between the primary and secondary electrodes 16 and 19, having the standard sine wave form 35 as indicated in Fig. 2. The voltage at the electrodes will be less than that induced at the transformer 31, because the winding 37 of the kick transformer acts as a reactance. The current control means 42 in the circuit 41 of the kick transformer 38 is adapted to operate so that the kick transformer 38 will be periodically excited. When there is a periodic excitation of the kick transformer 38, the current flowing to and from the electrodes 16 and 19 is very-quickly and very greatly increased and very quickly decreased. The result is that the potential of the electric field is periodically increased instantaneously to a very high potential or potential gradient. In Fig. 3 the line 45 illustrates the wave form of the potential impressed on the field when alternating current is supplied to the kick transformer 38 and when the current control means operates in synchronism with the potential indicated by the numeral 45,

this current-control means establishing the circuit 41 once each alternation of the current produced by the main transformer 31. The

,line 45 has extremely high peaks 46 which occur when the current to the electrodes is reinforced by the kick transformer 38. From Fig. 3-it will be evident that these peaks increase the potential of the electric field very greatly and very quickly. Each alternate peak 46 in Fig. 3 is of the same polarity.

It is not absolutely necessary that the peaks 1 of the kick transformer be impressed exactly on the peaks of the normal wave form used. In Fig. 4 a line 48 represents the potential of the electric field when the surges or kicks, indicated at 49, occur once in every two cycles of the main transformer 31. In Fig. 5 a line 51 represents the potential of the electric field when it is provided with surges or kicks as indicated at 52, which are of unidirectional polarity and which occur at every alterna:

larger masses precipitate into the lower part of the shell 12, being drawn therefrom through the water outlet 15. The oil as it is relieved of the water rises to the upper part of the shell 12 and is drawn off through the oil outlet pipe 14.

In my invention I combine the advantages of a low potential electric field and a high potential electric field and therefore I am able to very efficiently, thoroughly and cheaply dehydratepetroleum oil or other oil.

My invention is not limited to the use of transformers for. producing the primary or secondary potentials which are simultaneously impressed on the circuit including the electrodes. Any source of potential having a definite wave form might be substituted for the main transformer 31, and any auxiliary means of varying this wave form might be substituted for the kick transformer 38. This auxiliary means may be either inductivelyor capacitively connected to this circuit without departing from the spirit of my invention.

In this capacity it should be noted that the primary 40 of the kick transformer 38 is both inductively and capacitively connected to the circuit including the secondary 30 and the electrodes, the induction coupling taking place through the magnetic flux linking both the primary 40 and secondary 37 and the capacitive coupling taking place through the inherent capacity between these primary and secondary windings.

I claim as my invention:

1. A dehydrating apparatus including a pair of electrodes between which is positioned an emulsion to be treated; means for creating an electric field between said electrodes; and means for periodically increasing the potential of said electric field.

2. A dehydrating apparatus including in combination: a pair of spaced electrodes insulated from each other and defining a treating space in which is positioned the emul- .sion to be treated; a source of potential connected in a circuit with said electrodes and impressing an alternating potential thereacross; and means in said circuit-for periodically peaking the alternating potential impressed across said electrodes by said source of potential.

3. A dehydrating apparatus including in combination: a pair of spaced electrodes insulated from each other and defining a treating space in which is positioned the emulsion to be treated; a source of potential connected in circuit with said electrodes; and means associated with said circuit. for altering the wave form impressed'across said electrodes by said source of potential.

4. A combination as defined in claim 2 in which said means includes an auxiliary source of potential.

5. A combination as defined inclaim 2 in 50 form having peaks which said means operates in synchronism with said source of potential.

6. A dehydrating apparatus including in combination: a pair of spaced electrodes insulated from each other and definin a treating space in which is positioned t e emulsion to be treated; a source of vpotential connected in a circuit with said electrodes; an auxiliary source of potential connected to said circuit in a manner to greatly increase the potential across said electrodes when said auxiliary source of potential is energized; and means for periodically energizing said auxiliary source of potential for shortperiods of time. I

7. A dehydrating apparatus including in combination: a pair of spaced electrodes insulated from each other and defining a treatin space in which is ositioned the emulsion 20 to e treated; means or setting up a varying potential of primary wave form; means for superimposing a secondary potential of secondary wave form on said varying potential in a manner to produce a resultant wave form differing from either said primary wave form or said secondary wave form, said tential of secondary wave form being 0 greater magnitude than said potentialv of primary wave form; and means for impressing said resultant wave form across said electrodes. 8. A dehydrating a paratus including in combination: a air 0? spaced electrodes insulated from eac other and defining a treatin space in which is ositioned the emulsion to e treated; means or setting up a varying potential of primary wave form; means operating synchronously with said varying potential of primary wave form for superimposing a secondary potential of secondary 40 wave form on said varying potential in a manner to produce a resultant wave form dif- :fering from either said rimary wave form or said secondary wave ibrm, said otential of secondary wave form being 0 greater 45 magnitude than said potential of primary wave form; and means for impressing said resultant wave form across said electrodes.

9. A combination as defined in claim 7 in which said secondary potential has a wave which are substantially from six to eight times as hifgh as the peaks En said varying potential 0 primary wave orm.

10. A dehydrating afpparatus including in combination: a pair 0 spaced electrodes insulated from each other and defining a treating space in which is positioned the emulsion to be treated; a main transformer and an auxiliary transformer, the secondary wind- 50 ing of each transformer being connected in series in a circuit including said electrodes; means for continuously ener 'zing said main transformer; and means or eriodically energizing said auxiha trans ormer.

I 11. A combination as efined in claim 10 in which the peak potential of said auxiliary transformer is greater than the peak potential of said main transformer.

12. Inan apparatus for dehydrating an through which passes the current reaching said electrode; and means for periodically changing the otential difierence exist ng between the ends of said c'urrent-conductmg means.

In testimon whereof, I have hereunto set my hand at 0s Angeles, California, this 24th day of August 1926.

HARMo F. FISHER. 

